1. Field of the Invention
The present invention relates to a bucket tool for a power shovel that can be used for excavation as well as for ground-leveling operation.
2. Description of the Prior Art
Referring to FIG. 5, a power shovel 1 used for construction work is equipped with a boom 2 that can be raised and lowered, and wherein a base end of an arm 3 is pivotably connected to an end of the boom 2, and a base portion of a bucket 4 is pivotably connected to another end of the arm 3. The front part of the bucket 4 is provided with a plurality of protruding excavation teeth 5 in an interval like a fork.
The power shovel 1 is horizontally turned to change the direction of the boom 2, the boom 2 is raised and lowered, and the arm 3 and the bucket 4 are turned, in order to excavate sand, soil, gravel, rock, etc. The excavated sand, soil, etc. are scooped up by the bucket 4 and are loaded onto a dump truck, etc.
After the excavation operation, the ground is usually leveled by any one of the following three methods.
(1) The ground is leveled by replacing the excavation bucket 4 with the excavation teeth 5 by a leveling bucket without the excavation teeth 5. PA1 (2) A square steel plate having a width nearly equal to the width of the bucket 4 and a length nearly equal to the length of the excavation teeth 5, is welded onto the excavation teeth 5 protruding beyond the excavation bucket 4, and the ground is leveled by the end surface of the steel board. PA1 (3) Detachable split teeth having a large width are fitted onto the excavation teeth 5 so as to overlap neighboring ones, and the ground is leveled by using the split teeth.
When the ground is leveled by replacing the bucket by the leveling bucket without the excavation teeth 5 of (1), however, each power shovel 1 must be provided with both the excavation bucket 4 and the ground-leveling bucket, accompanied by an increase in cost and a cumbersome operation for replacing the bucket on the site.
According to the method of welding the steel plate onto the excavation teeth 5 of the excavation bucket 4 of (2), the steel plate must be welded at the site, which is cumbersome. To carry out the excavation operation, next, furthermore, the steel plate welded onto the excavation teeth 5 must be removed which involves a cumbersome operation.
According to the method of leveling the ground by mounting broad detachable split teeth on the excavation teeth 5 of (3) so as to overlap each other, the split teeth are not flatly overlapped but are ruggedly overlapped by each other. Therefore, the ground is not flatly leveled, which is not suitable for a leveling operation where flatness is required. Besides, since the split teeth are broad, an increased load is exerted on each split tooth, and the portions where the split teeth are mounted on the excavation teeth 5 cannot withstand the use for extended periods of time.